Simian models are especially attractive for AIDS vaccine development because of the keen relatedness between our species. Indeed, chimpanzees are our closest relatives in the animal kingdom and as such are a uniquely theoretically accurate model for studying HIV infection. This request is made to continue studies at The Coulston Foundation with experimental chimpanzees that are being utilized by NIAID grantees and intramural investigators in ongoing studies. Upon concept approval, this activity was initiated by participation in an ongoing contract that the National Cancer Institute maintained with the chimpanzees facility on the grounds of the Holloman Air Force Base in Alamogordo, New Mexico which was operated at that time by New Mexico State University (NMSU). NIAID specified the work to be done, and NCI was able to fulfill the workscope via its contract to operate the Frederick Cancer Research and Development Center, which already had an existing subcontract to NMSU; an intra-Agency Agreement between NIAID and NCI provided the funds. In 1993, NMSU transferred its control of the chimpanzee facility to the Coulston Foundation with NCI approval. The NCI contract is expiring and NCI is phasing out support of chimp studies; this request is submitted to convert to a direct NIAID contract with Coulston. Loss of the animals at this point would render the current studies useless and would deny the agency from reaping further knowledge from these scarce animals.